In 1982, corn plant density ranged from 19,400 to 22,200 plants/A. Minnesota has consistently had higher average corn plant density than other states (Figure 1). In Wisconsin plant densities were 20,300 plants/A in 1982. Plant density has since increased at the rate of 267 plants/A*yr. Iowa and Illinois have had the greatest rates of change at 308 plants/A*yr.
|Figure 1. Corn plant density changes over time for states in the U.S. Midwest Corn Belt. The rate of change (slope) in plants/A*yr since 1982 is reported for each state. Data derived from USDA-NASS.|
- What plant density achieves maximum yield (MYPD)?
- What plant density achieves the economic optimum (EOPD)?
- Are the MYPD and EOPD the same for grain and silage?
- Do hybrids differ for MYPD and EOPD?
- Do fields differ for MYPD and EOPD?
- How does risk change, especially during years of drought or lodging?
- What happens to plant bareness?
- Do precision farming variable rate technologies make a difference?
One approach that might be useful for your farm is to plant fields with a target plant density based upon your experience. Then for one round (or pass) in a couple parts of the field, increase plant density 10% (Figure 2). If harvest yield is affected, then adjust plant density the following season. If not, you are out the difference of ROI for seed.
|Figure 2. An example of using reference strips for testing maximum yield plant density. Plant most of field to plant density based upon experience. In one strip (ideally 2 or 3) increase plant density 10%. Measure yield at harvest.|